ayers



March 24, 1964 J. s. AYERS 3,125,949

OFFSET PRINTER FOR MARKING SMALL OBJECTS Filed Jan. 15, 1962 INVENTOR IE JOHN S. AYERS M,M;M./

A Horneys United States Patent 3,125,?49 OFFSET PRHNTER FOR MARKING SMALL OBJECTS John S. Ayers, Scott Township, Allegheny County, PZL, assignor to .las. H. Matthews & (30., Pittsburgh, Pa., a corporation of Pennsylvania Filed Jan. 15, 1962, Ser. No. 166,122 8 Qlaims. (Cl. NFL-33} This invention relates to offset printing machines and is for a printing machine especially designed for imprinting markings or indicia on small objects, including, but not necessarily limited to, small objects which may have a somewhat undulated or irregular surface.

Many small objects require that the surface be marked with some indicia or identification. In many instances the surface to be marked is non-planar or slightly undulating. Electrical transistors, for example, must have clearly readable indicia printed thereon. Typically they may be roughly about /8 of an inch square with a slightly wavy surface of insulating material. Metal type may not be used because it will not yield to surface irregularities or conform to the contour of the workpiece, or the surface to be printed upon is too unyielding. Rubber type is likely to blur, because the type will spread out more in pressing against high spots than against lower areas, and it is diflicult, moreover, to regulate the ink supply to the type. Offset printing is desirable since the type wipes against an inking roll and then prints on a deformable blanket roll, which in turn transfers the markings to the object to be marked.

For purposes of illustration, transistors are specifically mentioned above as one item to which the machine is applicable, but the invention is useful for marking various small, flat, cylindrical or contoured parts where the printing is small but must be neat, clear, and legible.

While offset printing is not novel, a difiiculty in printing fine, sharp letters or markings on small objects has been to provide just the right amount of ink and the proper printing pressure to avoid blurring or smearing.

The present invention has for its primary object to provide an offset printer of unique construction for marking small objects with clear, sharp lettering or characters.

A further important object is to provide an oifset print ing machine for printing on small objects wherein the ink and printing pressure can be adjusted and controlled with micrometer exactness.

A still further object of this invention is to provide a machine of this character which is of simple construction and wherein the type or marking characters may be readily replaced or interchanged.

These and other objects and advantages are achieved by this invention, an embodiment of which is shown in the accompanying drawings. In the drawings:

FIG. 1 is a side elevation of the machine;

FIG. 2 is a top plan view of the machine;

FIG. 3 is a fragmentary vertical section in the plane of line IIIIII of FIG. 1; and

FIG. 4 is a fragmentary vertical section in the plane of line IV1V of FIG. 1.

The machine is designed to be placed alongside or adjacent a conveyor line, or otherwise mounted in a position to print on regularly-spaced pieces moving past or presented to a marking station at regular intervals with the machine being driven synchronously with the conveyor or other workpiece carrying mechanism. The machine may be designed to operate in either a horizontal position or a vertical position, and is here shown in a horizontal position, but in FIG. 1 is inverted from its intended manner of use, and the machine is shown apart from the conveyor or other mechanism that moves the articles to be printed upon in succession to the printing machine.

3,125,949 Patented Mar. 24, 1964 As shown in the drawings, the machine comprises a base member or frame 2, which is here represented as an integral casting. It is provided with a hub portion 3 by which it may be mounted for rotatable adjustment about a vertical pivot shaft, not shown, for positioning the printer adjacent the conveyor or other mechanism in conjunction with which the printer is used.

There are four rotatable shafts passing transversely through the base member, these being designated 4, 5, 6 and 7, and the frame, as shown, has bosses 8 formed thereon to provide adequate bearing length for these shafts, ball bearings being preferably provided in the frame near opposite ends of the shafts. The shafts, however, project beyond each side of the frame or base. Each of them has a gear wheel 4a, 5a, 6a and 7a respectively at one end, these gears meshing with one another, and gears 5a, 6a and 7a are all of the same diameter so as to rotate at the same speed and in isochronism. As viewed in FIG. 1, gear 6a and its shaft 6 are directly behind gear 7a and its shaft so as not to be visible in this figure. One of these shafts, such as shaft 5, also has a driving element, for example a pulley 9 keyed thereto, so that it may be driven from the conveyor or machine to which the printer is attached. Rotation of the shaft 5 imparts rotation through the gears to all of the other shafts.

On the opposite surface of the frame there is an ink reservoir 10, and there is a dip roll or ink roll 11 in the reservoir keyed to the end of shaft 4 opposite the gear 4a. A doctor blade 12 bears against the periphery of the dip roll with a pressure that may be regulated by an adjusting screw means 13, as is customary in the printing art to regulate the thickness of the film of ink carried by the periphery of the dip roll out of the reservoir. The reservoir may be removably secured to the frame 2 by studs carried by the frame passing through the reservoir 10 outside the ink-retaining space therein and on which are wing nuts 14. The roll 11 has a smooth metal periphery.

In operation the dip roll rotates in the direction of the arrow in FIG. 2. Paste ink is preferably employed, and the reservoir is provided with an elbow fitting 15 into which the discharge end of a collapsible ink tube 17 is removably screwed.

On the end of shaft 5 opposite the gear 5a there is a segmental ink pad carrier designated generally as 18. This carrier comprises a hub member 19 keyed to the end of the shaft 5 and which, as here shown, is generally rectangular. It has a hole in the plane of its rotation passing therethrough at each side of the shaft 5 and an adjusting pin 20 is slidably passed through each hole. These pins have their corresponding end portions at one end secured in a segmental carrier block 21. The other ends of the pins pass through a cross bar 22 and have nuts 20a to retain the cross bar in place, while compression springs 23 around the pins, confined between the hub and the cross bar, yieldably urge the cross bar outwardly away from the hub, tending thereby to draw the carrier block 21 inwardly toward the hub. There is a bolt or machine screw 24- between the two guide pins 20 along which the cross bar may slide, the inner end of this bolt being screwed into a threaded socket 2.5 in the hub. The head of this bolt bears against the outer face of the cross bar and restrains it from moving outwardly under the pressure of the springs 23.

The peripheral arc of the segmental carrier block 21 is of the general structure hereinafter more fully described but is substantially bifurcated in the plane of rotation of the carrier, and in the space so provided there is a replaceable rubber or rubber-like ink transfer pad 26, the outer face of which projects beyond the carrier block. It is so adjusted, by turning bolt 24 and nuts 20a, that when it is carried around by rotation of the shaft 5 it bears against the periphery of the dip roll and in so doing picks up a film of ink from the surface of the dip roll.

On the end of the shaft 6 opposite the gear wheel 60 is a segmental type carrier assembly 27 generally similar to the assembly 18, in that it has a rectangular hub portion 28 keyed to shaft 6, parallel pins 29 passing therethrough in the plane of rotation of the assembly. There is a type holder block 30 to which one end of each of these pins passes, and the other ends of the pins pass through a cross bar 44. There are compression springs 31 around the pins 29 confined between the hub and the cross bar. There is a central adjusting screw 32 similar to screw 24 at the center of the cross bar, and on the free ends of the pins 29 which are threaded, are nuts 2%.

The type holder block 30 is best seen in FIGS. 2 and 3. The block has a forwardly-projecting ledge portion 3% in which is a wedge-shaped notch or socket for receiving the metal type element 33'shaped to fit into the socket with the type bearing face projecting beyond the ledge and curved substantially to the curvature of its circle of revolution about the axis of shaft 6. There is a removable clamping plate Silb on the ledge for clamping the type element in the socket. It is held in place by machine screws 34 that pass through the ends of the plate 30b into the solid ledge at each side of the socket.

On the end of shaft 7 opposite gear 7a there is a segmental blanket or offset printing roll assembly 35. It comprises a rectangular hub portion 36 keyed to the shaft 7' and is otherwise generally similar to the ink transfer assembly 18. There are parallel slide pins 37 passing through the hub in the plane of its rotation and corresponding ends thereof are secured to a blanket segment carrier 38. The opposite ends of the pins are threaded and pass through a cross bar 39. They have nuts 37a at their outer ends and there are compression springs 4% surrounding each pin urging the cross bar outwardly away from the hub. There is a central cross bar adjusting screw 41 corresponding to screw 24 in the assembly 18 above described.

The blanket segment carrier block 38 has an outwardlyprojecting ledge 38a on the top surface of which is a rib 3812. On the top of the block there is a clamping plate 380 held in place by a thumb nut or machine screw 42. This plate has a rib 38d on its under face, confronting rib 38b. The segmental printing blanket 43 is confined in the space between ledge 38a and clamping plate 33c. This blanket segment which is made of rubber or rubber-like material, is grooved on its top and bottom surfaces to interfit with ribs 38d and 38b, respectively. The carrier is thus of a generally bifurcated construction at its outer end with the blanket segment confined in the space between the clamping plate and the ledge and its periphery projecting beyond the periphery of the carrier block itself. The segment 43 is of less peripheral extent than the block in which it is mounted so that it can be adjusted slightly sideways to register with the printing segment and work piece.

The ink transfer pad holder is here shown to be of the same construction as the offset printing pad segment, so that it may be adjusted sideways to a slight extent.

The parts are all angularly positioned on their respective shafts so that the ink transfer pad on shaft will contact the revolving dip roll on shaft 4 and then move into confronting and contacting engagement with the type on the peripheral surface of the type block. The type block will in turn move into contact with the periphery of the printing pad. The printing pad in its circle of revolution will then contact the article to be printed upon and transfer the imprint it received from the type block onto the article.

By adjusting the central screw, corresponding to the screw 24 of each of the several rotating segments, micrometer adjustment may be made of the several segment assemblies. By screwing the central screw inwardly, the inking or printing element is projected outwardly, and

i by screwing it outwardly the springs act to draw the element being adjusted inwardly. It is thus possible to so exactly regulate the adjustment that only the precise amount of ink is carried from the dip roll to the transfer pad, from the transfer pad to the type, and from the type to the offset printing pad to make a clear, sharp imprint on the article being marked. Obviously the machine as here constructed is primarily applicable to very small imprints because the curvature of the peripheries of the ink pad, type block and printing pad is selected for a radius of the optimum diameter for the work to be done, and the adjustment above described increases or shortens this radius from the optimum and the arc of the periphery of the element then no longer exactly corresponds with the circle of revolution through which it moves. Consequently while there is no limitation within practical limits of vertical height of the printing block or other elements, that is, in a direction parallel with the axis of rotation, the angular width of the printing block, and of the ink transfer pad and offset printing pad should not exceed, and is preferably less than 30 of arc. The range of adjustment radially need be very slight to satisfy the requirements for clear, sharp printing.

The nice, exact adjustment provided by the machine adapts it to the printing of small letters or marks in a small space, whereas on larger objects with large letters or characters there is less need for fine adjustment or regulation of the ink transfer and conventional printing apparatus may be used. To avoid possible interference of one revolving element with another the overall length and width of the assemblies 18, 27 and is with their respective pads or type elements preferably not exceeding the pitch diameter of the gears 5a, 6a and 7a respectively, although the segmental elements may be projected slightly beyond such diameter, but the radius of curvature of the segments of the elements must be substantially equal, as are the fixed diameters of the gears 5a, 6a and 7a, so that when one element is adjusted radially compensating adjustment of the other elements may also be made to assure, for practical purposes uniform contact between the elements to thereby provide uniform intensity of a marking at the both ends and the center of the imprint.

While I have shown and described one specific embodiment of my invention, it will be understood that the invention may be otherwise embodied within the scope of the following claims.

I claim:

1. An offset printer comprising a supporting frame, a plurality of parallel rotatable shafts mounted in the frame, a gear on each of the several shafts with the several gears intermeshing to form a gear train for rotating the several shafts in unison, means for driving one of the shafts, an ink fountain, a dip roll on one of the shafts rotatable in the ink fountain, an ink transfer pad assembly on the second shaft having a segmental pad element at its peripher a type holding assembly on the third shaft having a segmental type element at its periphery of substantially the same radius of curvature as the pad, an offset blanket element assembly on a fourth shaft having a segmental printing blanket element at its periphery also of substantially the same radius of curvature as the pad and type elements, the several assemblies being so positioned on their respective shafts that the pad element rolls first against the dip roll and then against the type element of the assembly on the third shaft, and the segmental type element moves first against the pad element and then against the offset blanket segment, which last-named segment rotates from its position of contact with the printing element to a printing station, said gears for rotating the second, third and fourth shafts being in meshing relation with one another and each being of the same pitch diameter as the other whereby they rotate in isochronism.

2. An offset printer as defined in claim 1 in which the segmental elements of each of the said assemblies are adjustable radially relative to the shafts on which the respective assemblies are carried.

3. An oifset printer as defined in claim 1 in which the segmental elements of each of the said assemblies are adjustable radially relative to the shafts on which the respective assemblies are carried, and screw-adjusting means for effecting said radial adjustment of the segmental elements.

4. An offset printer as defined in claim 1 in which the segmental elements of each of the said assemblies are adjustable radially relative to the shafts on which the respective assemblies are carried, said segmental elements being curved to conform to the curvature of the circle of revolution through which they are carried by rotation of their respective shafts in one position of radial adjustment of the segments.

5. An oifset printer as defined in claim 1 in which the segmental elements of each of the said assemblies are adjustable radially relative to the shafts on which the respective assemblies are carried, said segmental elements being curved to conform to the curvature of the circle of revolution through which they are carried by rotation of their respective shafts in one position of radial adjustment of the segments and being or" an arcuate extent such that within the range of their radial adjustability they each may make full surface contact with each of the other elements with which it contacts.

6. An offset printer for printing on small objects as defined in claim 1 wherein each of said assemblies comprises a hub section keyed to the shaft on which it is carried, a block having a peripheral portion for holding the element which is mounted in the assembly, guide pins on the block slidably passing through the hub, one at each side of the shaft and projecting from the side of the hub opposite the block, and means on the projecting ends of the pins and on the hub for effecting adjustment of the pins and block radially of the shaft.

7. An offset printer for printing on small objects as defined in claim 1 wherein each of said assemblies comprises a hub section keyed to the shaft on which it is carried, a

block having a peripheral portion for holding the element which is mounted in the assembly, guide pins on the block slidably passing through the hub, one at each side of the shaft and projecting from the side of the hub opposite the block, the projecting ends of the pins having nuts at their ends, a cross bar through which the pins pass bearing against the nuts, spring means confined between the cross bar and hub urging the cross bar radially away from the hub, and screw means engaging the cross bar and hub for adjustably limiting the movement of said cross bar away from the hub.

8. An offset printer for printing on small objects as defined in claim 1 wherein each of said assemblies comprises a hub section keyed to the shaft on which it is carried, a block having a peripheral portion for holding the element which is mounted in the assembly, guide pins on the block slidably passing through the hub, one at each side of the shaft and projecting from the side of the hub opposite the block, the projecting ends of the pins having nuts at their ends, a cross bar through which the pins pass bearing against the nuts, spring means confined between the cross bar and hub urging the cross bar radially away from the hub, a bolt having a head bearing against the outer surface of the cross bar and threaded into the hub confining the cross bar against the action of the spring means, the adjustment of the nuts on the pins and the screwing of said bolt into or out of the hub providing a micrometer adjustment for the block in a radial direction.

References Qited in the file of this patent UNITED STATES PATENTS 474,163 Cunny May 3, 1892 1,092,830 Ford Apr. 14, 1914 2,160,725 Flint May 30, 1939 2,351,224 Nystrom June 13, 1944 2,475,524 Scott et at July 5, 1949 2,558,542 Davis June 26, 1951 2,656,789 Bechtold Oct. 27, 1953 

1. AN OFFSET PRINTER COMPRISING A SUPPORTING FRAME, A PLURALITY OF PARALLEL ROTATABLE SHAFTS MOUNTED IN THE FRAME, A GEAR ON EACH OF THE SEVERAL SHAFTS WITH THE SEVERAL GEARS INTERMESHING TO FORM A GEAR TRAIN FOR ROTATING THE SEVERAL SHAFTS IN UNISON, MEANS FOR DRIVING ONE OF THE SHAFTS, AN INK FOUNTAIN, A DIP ROLL ON ONE OF THE SHAFTS ROTATABLE IN THE INK FOUNTAIN, AN INK TRANSFER PAD ASSEMBLY ON THE SECOND SHAFT HAVING A SEGMENTAL PAD ELEMENT AT ITS PERIPHERY, A TYPE HOLDING ASSEMBLY ON THE THIRD SHAFT HAVING A SEGMENTAL TYPE ELEMENT AT ITS PERIPHERY OF SUBSTANTIALLY THE SAME RADIUS OF CURVATURE AS THE PAD, AN OFFSET BLANKET ELEMENT ASSEMBLY ON A FOURTH SHAFT HAVING A SEGMENTAL PRINTING BLANKET ELEMENT AT ITS PERIPHERY ALSO OF SUBSTANTIALLY THE SAME RADIUS OF CURVATURE AS THE PAD AND TYPE ELEMENTS, THE SEVERAL ASSEMBLIES BEING SO POSITIONED ON THEIR RESPECTIVE SHAFTS THAT THE PAD ELEMENT ROLLS FIRST AGAINST THE DIP ROLL AND THEN AGAINST THE TYPE ELEMENT OF THE ASSEMBLY ON THE THIRD SHAFT, AND THE SEGMENTAL TYPE ELEMENT MOVES FIRST AGAINST THE PAD ELEMENT AND THEN AGAINST THE OFFSET BLANKET SEGMENT, WHICH LAST-NAMED SEGMENT ROTATES FROM ITS POSITION OF CONTACT WITH THE PRINTING ELEMENT TO A PRINTING STATION, SAID GEARS FOR ROTATING THE SECOND, THIRD AND FOURTH SHAFTS BEING IN MESHING RELATION WITH ONE ANOTHER AND EACH BEING OF THE SAME PITCH DIAMETER AS THE OTHER WHEREBY THEY ROTATE IN ISOCHRONISM. 